Author: crosby.124

Coyotes in Columbus

One of my favorite courses at Ohio State University (OSU) is the mammalogy course offered in the School of Environment and Natural Resources, which is instructed by Dr. Stan Gehrt. A big part of this course is a field study, where students use different sampling techniques to survey wildlife around Columbus. Our group chose to survey mammals in Chadwick Arboretum, which is located on OSU’s west campus. In addition to daytime in-person surveys, our group set up camera traps in an effort to capture the area’s nightlife. We were mostly expecting to capture images of deer, and maybe raccoons, so you can imagine our surprise when a coyote showed up in our photos (Figure 1)!

Figure 1. Camera trap photo of a coyote in Chadwick Arboretum (my own)

Urban coyotes are far more common than some people realize, and research groups in urban centers around the country have studied this phenomenon. For example, Dr. Gehrt’s lab studies urban coyotes in Chicago, Illinois. Additional research efforts include the Urban Coyote Initiative and the Denver Urban Coyote Project (See the links below for more information on these projects!).

Not surprisingly, not all animals can thrive in the urban landscape. Urban environments can cause stress in animals (Schell et al., 2013; Birnie-Gauvin et al., 2016). When an animal becomes stressed, stored energy in its body is mobilized (Randall et al., 2001). This energy fuels the animal’s “fight or flight” response. This stress response allows the animal to deal with the stressor, which is beneficial in the short term. However, long-term stress can have negative health impacts, such as decreased functioning of the immune system, that result in decreased fitness (Randall et al., 2001).

When faced with anthropogenic disturbance, coyotes do present a stress response (Schell et al., 2013). However, research has shown that coyotes thrive in urban environments (Morey et al., 2007; Gehrt et al., 2011). This success in urban environments may be due, in part, to increased survival (Gehrt et al., 2011; Rodewald & Gehrt, 2014). Although adult coyotes have similar survival rates in urban and rural environments, research has shown that juvenile coyotes have higher survival rates in urban environments (Gehrt et al., 2011).

In addition to changes in reproduction and survival, urban species often behave differently than their rural counterparts (Ditchkoff et al., 2006; George & Crooks, 2006). For example, research has shown that coyotes have lower activity levels in areas where human activity is high (George & Crooks, 2006). Other species, such as bobcats, may become more nocturnal in urban areas in order to avoid high human activity during the day (George & Crooks, 2006). Urban species may also change their diets and foraging strategies in order to take advantage of food sources such as garbage or garden fruits and vegetables (Ditchkoff et al., 2006). These behavioral modifications help urban species to take advantage of new resources and avoid human-induced stress, which ultimately enables them to survive, and sometimes even thrive, in urban environments.

Check out the following links for more information:

References

Birnie-Gauvin K, Peiman KS, Gallagher AJ, de Bruijn R, Cooke SJ (2016) Sublethal consequences of urban life for wild vertebrates. Environ Rev 24: 416 – 425.

Gehrt SD, Brown JL, Anchor C (2011) Is the urban coyote a misanthropic synanthrope? The case from Chicago. Cities Environ 4.

Morey PS, Gese EM, Gehrt SD (2007) Spatial and temporal variation in the diet of coyotes in the Chicago metropolitan area. Am Midl Nat 158: 147 – 161.

Randall D, Burggren W, French K (2001) Eckert Animal Physiology: Mechanisms and Adaptations. W. H. Freeman and Company, New York.

Rodewald AD, Gehrt SD (2014) Wildlife Population Dynamics in Urban Landscapes. In: McCleery RA, Moorman CE, Peterson MN, eds. Urban Wildlife Conservation. Springer US, pp 117 – 147.

Schell CJ, Young JK, Lonsdorf EV, Santymire RM (2013) Anthropogenic and physiologically induced stress responses in captive coyotes. J Mammal 94: 1131 – 1140.

“Cutbow” Trout: Sportfish Hybridization Increases with Climate Change

Rainbow Trout are a popular sportfish in the United States. The species has been stocked in lakes and streams outside of its native range since the late 1800s. Interestingly, in many areas where stocking has stopped, Rainbow Trout populations continue to thrive. This is because stocked Rainbow Trout have been able to survive and reproduce in their introduced ranges (Muhfeld et al., 2017). Over time, these stocked individuals and their offspring have immigrated out from the stocked locations and colonized new habitats. Rainbow Trout populations are now established across much of the United States, and the species is considered invasive in many areas.

Rainbow Trout populations are negatively impacting native trout species in these systems. This is because Rainbow Trout can hybridize with other closely related trout species. Hybridization occurs when two separate species reproduce. Hybridization between a native and invasive species can be dangerous. Native species are usually adapted to their habitat. However, invasive species often do not have the same set of adaptations. Thus, when a native and non-native species hybridize, some of the beneficial traits of the native species are lost or diluted by traits from the invasive species.

A team of researchers and USGS scientists have been studying this phenomenon in trout populations in the Northern Rocky Mountains since the 1980s (Muhfeld et al., 2017). Specifically, the team is interested in “Cutbow” Trout, which are produced when native Cutthroat Trout and invasive Rainbow Trout reproduce (Figure 1). Cutbow Trout are generally fertile, which means they can produce offspring of their own. This is an issue because as hybrids reproduce, the gene pool continues to get polluted.

Figure 1. Hybridization between native Cutthroat Trout and invasive Rainbow Trout produces “Cutbow” Trout.

Scientists expect climate change to favor Rainbow Trout, which will result in more hybridization between the invasive and native trout species (Bear et al., 2007; Muhfeld et al., 2014; Muhfeld et al., 2017). All species have a range of temperatures that they can live comfortably in (Randall et al., 2001). This range varies within and between species. At temperatures above or below this range, individuals experience decreased performance. Climate change results in warmer temperatures, which Rainbow Trout can tolerate better than Cutthroat Trout (Bear et al., 2007). In addition, Rainbow Trout have a higher capacity for growth at higher temperatures than native Cutthroat Trout (Bear et al., 2007). As waters continue to warm, Rainbow Trout are expected to continue to spread into new areas. Rainbow Trout will encounter more native trout populations in these areas, which will result in more hybrid trout populations (and continued decline of native trout populations).

Fortunately, invasive Rainbow Trout populations are being managed in several ways (Muhfeld et al., 2017). For example, barriers are often installed so that Rainbow Trout cannot reach uninvaded areas. Additional management strategies include habitat restoration and protection and fishing efforts targeting the invasive Rainbow Trout. These efforts will be critical for biodiversity conservation, especially in the face of climate change (Muhfeld et al., 2017).

 

Check out the following links for more information:

 

Figure created with images attributed to the National Park Service (http://www.yellowstone.co/fish.htm#wscut)

 

References

Bear EA, McMahon TE (2007) Comparative thermal requirements of westslope cutthroat trout and rainbow trout: implications for species interactions and development of thermal protection standards. Trans Am Fish Soc 136: 1113 – 1121.

Muhfeld CC, Kovach RP, Al-Chokhachy R, Amish SJ, Kershner JL, Leary RF, Lowe WH, Luikart G, Matson P, Schmetterling DA, Shepard BB, Westley PAH, Whited D, Whiteley A, Allendorf FW (2017) Legacy introductions and climatic variation explain spatiotemporal patterns of invasive hybridization in a native trout. Glob Change Biol.

Muhfeld CC, Kovach RP, Jones LA, Al-Chokhachy R, Boyer MC, Leary RF, Lowe WH, Luikart G, Allendorf FW (2014) Invasive hybridization in a threatened species is accelerated by climate change. Nat Clim Change 4: 620 – 624.

Randall D, Burggren W, French K (2001) Eckert Animal Physiology: Mechanisms and Adaptations. W. H. Freeman and Company, New York.